The present invention is directed to a wireless response system and method including providing wireless communication between a plurality of handheld response units, or keypads, and a base unit and in particular to such a system and method which allows each keypad to communicate with a plurality of base units.
Commonly assigned U.S. Pat. No. Re. 35,499 issued to Derks and entitled A REMOTE 2-WAY TRANSMISSION AUDIENCE POLLING AND RESPONSE SYSTEM and commonly assigned U.S. Pat. No. 5,724,357 issued to Derks and entitled REMOTE RESPONSE SYSTEM AND DATA TRANSFER PROTOCOL each disclose a communication protocol for wireless communication between a base unit and a plurality of response units in order to collect responses entered by users at the response units. In order to ensure reliable receipt of the responses, the base unit examines the data received from the response units for validity and sends an acknowledge message to the response unit sending that data.
In order to increase the geographic size of the system, such as to encompass a large space such as an auditorium, stadium, or the like, response systems have been proposed that utilize a plurality of base units, each capable of receiving data from the response units. One such system disclosed in commonly assigned United States Patent Application Publication No. US 2003/0236891 A1 entitled WIRELESS ASYNCHRONOUS RESPONSE SYSTEM includes a plurality of base units in a large facility, each of which is capable of receiving a wireless signal from any of a large number of response systems. However, the system disclosed therein is an asynchronous system in which data is sent from the response unit to one of the base units without receiving a base transmission from the base unit. Such system has limitations that are not found in a response system in which data is sent from the response units to a base unit in response to a base transmission from the base unit.
In another system disclosed in commonly assigned United States Patent Application Publication No. US 2003/0153321 A1 entitled WIRELESS RESPONSE SYSTEM AND METHOD, a plurality of base units are synchronized such as by a cable or other communication channel between the base units. This allows synchronized base transmissions so that one base unit is not sending a base transmission while the other base unit is listening to receive data from the response units. However, this requires coordination between the base units.